Endoscopy is a medical field which allows the acquisition of high-quality video images of internal features of a human body, without the need for invasive surgery. A basic tool of endoscopy is an endoscopic camera system, which includes a scope that is inserted into the body of a patient. Some endoscopic procedures involve the use of a flexible scope, as in the field of gastroenterology, for example. Other procedures, such as arthroscopy or laparoscopy, involve the use of a rigid scope. The scope is normally connected to a camera head that includes electronics for acquiring video image data through the scope.
The connected scope and camera head may be held and manipulated during endoscopic surgery by a human surgical assistant or by a holding tool, such as a robotic positioning system. The scope has optical properties which allow it to introduce light into the body of the patient and to transmit light from the body cavity to the camera head. A high intensity light source may be coupled to the scope by a fiber optic cable to introduce light into the body. The camera head is coupled through a flexible transmission line to a camera control unit, which is often mounted on a mobile cart. The control unit processes video data provided by the camera head to generate images, which are displayed on a video monitor. The control unit may also be coupled to various peripheral devices, such as a printer and a video cassette recorder (VCR).
During endoscopic surgery, the surgeon sometimes requires a more close-up ("zoomed") view of a feature inside the body. One way of accomplishing this is for the person or machine holding the scope to physically move the scope closer to the feature of interest. This approach has several disadvantages, however. For example, physically moving the scope consumes valuable time during surgery while the scope is repositioned. The repositioning process may involve several trial-and-error steps as the scope holder makes corrections in response to verbal feedback from the surgeon. It may be difficult for a human holder to maintain the scope in precisely the desired position, particularly when fatigue sets in. Further, moving the scope closer to the object of interest might interfere with the surgeon's ability to operate.
Some endoscopic camera systems provide the capability to zoom in on an object without having to move the scope closer to the object. Such systems use mechanical zooming, which generally involves adjusting the configuration of optics within the scope and/or its connection to the camera head. This may be done manually, such as by turning a knob or coupler, or electronically by pressing a button or other appropriate control. However, even these systems require time to adjust and are subject to a certain amount of trial-and-error in zooming.
Another problem is that zooming reduces the field of view of the scope. The scope has a maximum field of view corresponding to its non-zoomed setting. As the scope zooms in on an object, features that were near the periphery of the field of view may become lost outside the field of view. Consequently, the surgeon undesirably loses view of the general field of surgery within the body. Reacquiring the more general view requires reverting to a lower magnification setting. Thus, it is desirable to have an endoscopic camera system which overcomes these and other disadvantages of the prior art.